Winter and Annual General MeetingSource: Journal of Animal Ecology, Vol. 29, No. 2 (Nov., 1960), pp. 439-444Published by: British Ecological SocietyStable URL: http://www.jstor.org/stable/2236 .

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British Ecological Society 439 the woodland, some holes were dug in an area where rather impure limestone had weathered to produce a soil covering thicker than is usual, with about 6 in. of raw humus overlying the mineral soil. The woodland itself had a fairly open canopy with hazel rising to 12-15 ft in the centre of the wood, and ash to at least 40 ft. Associated trees included Crataegus monogyna, Betula Pubescens, Ilex aquifolium, Salix cafrea, Sorbus aucu,paria and Ulmus glabra. Goats and cows were numerous in the wood, and seedlings correspondingly rare, though some of ash and elm were seen. The ground flora included Holcus mollis, Oxalis acetosella and Hedera helix in abundance.

Tea at Gort provided a fitting conclusion to this meeting, which was blessed throughout with unusually fine weather.

P. J. NEWBOULD

WINTER AND ANNUAL GENERAL MEETING

8 AND 9 JANUARY 1960

Professor D. Lewis welcomed over a hundred members at the start of the Winter Meeting, 1960, in the Department of Botany, University College, London. Three papers were read during the afternoon of Friday, 8 January. In the first, concerned with 'The ecology of the St Kilda field-mouse', Dr J. Morton Boyd said that the St Kilda mice were first noticed by scientists in 1878 and both species, a house-mouse and a field-mouse, were described by the end of the century and were given the names Mus musculus muralis and Apodemus sylvaticus hirtensis by Barrett-Hamilton. In 1930 St Kilda was evacuated and it is thought that the house-mouse became extinct after 2 years. The field-mouse on the other hand was released from the predation of the domestic cats and dogs. There are now no predators of the mouse except the raven and large gulls. In 1955, 100 trap- nights achieved the same catch as 650 trap-nights using the same method in 1931, and in 1956-59 the-population remained consistently large by comparison with 1931. In 1956-57 a radar station together with camp and roads were built on the island of Hirta; about 300 men were stationed there in summer and 40 in winter. This upheaval did not appear to affect the field-mouse population significantly. A survey in 1957 showed that mice were widespread in and around stoneworks (natural and artificial) in all the main ecological zones; they were most numerous in the derelict village and scarcest on the summits and ridges. Arising from a certain amount of nuisance caused by mice in the camp, investigations were made into the movements of the animals with an eye to transplanting the community in the village area to other parts of the island. Trap surveys showed that animals could range over 3 acre in the village in a few nights and that if removed up to 2 a mile from the village area would return to the site at which they were trapped, in some cases within a few hours.

The breeding season is similar to mainland populations and is determined by the females: conception is probably in late April, the young appearing in the traps in late June. Parasites include three fleas and two mites. There are heavy infestations of the nematode Rictularia cristata and the cestode Hymenolepis diminuta. Cysticercus fasciolaris, the larva of Taenia crassicolis (the cat tape-worm), found in 1931, has not been found in recent dissections and is probably extinct at St Kilda.

Professor N. A. Burges, Dr E. W. Bentley, Mr I. J. Linn, Mr R. A. Davis, Mr M. J. Delaney, Dr G. M. Dunnet, and Mr P. A. Jewell took part in subsequent discussion, in which the importance of the shelter provided by cleats and other stoneworks was emphasized.

Dr P. J. Newbould, speaking on 'The ecology of Hartland Bog and Fen, Dorset', commented that recent work, especially in Scandinavia, has demonstrated correlations between the chemical analysis of mire waters and vegetation. Water movement, which is difficult to measure, is probably also important in this connection.

Dr Newbould, referring to lantern slides, showed that on Hartland Moor, in Dorset, two converging arms have differing vegetation. The northern, or valley bog, arm has a continuous carpet of Sphagnum with occasional plants of Schoenus nigricans, whereas in the southern, or fen, arm there is only a narrow zone of Sphagnum lateral to the main area of water flow which is dominated by dense tussocky Schoenus with abundant

P* J.A.E.

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440 British Ecological Society

Cam.pylium stellatum. The vegetation below the point where the two arms join is inter- mediate. There is a reasonable correlation between the distribution of vegetation types and the pH and calcium content of the water. The source of the calcium-rich water of the fen arm may be the chalk foundation of the main road.

Estimates of the (mainly annual) standing crop of three sites were similarly correlated with water analyses, the productivity of the fen being apparently greater than that of the valley bog. The ash and base contents of the plant material were determined. These two sets of data were combined to give an estimate of base turnover in the three sites. Calcium, expressed either as turnover per unit area, or as a percentage of the dry weight of the standing crop, is considerably higher in the fen than the valley bog. Differences in sodium and potassium are smaller. A comparison of these figures with the water analyses showed that potassium is concentrated by the vegetation much more than calcium or sodium. It seems unlikely that calcium supply has a direct limiting effect on the vegetation. The differences in base turnover can be explained by differences in water analysis in the three sample areas, without invoking differences in water movement, though the latter must occur.

Finally the density, height growth, dry weight per unit area and tussockiness of Schoenus nigricans on Hartland Moor are closely related to the base status of its environment.

The possibility of estimating the rate of supply and replacement of water was discussed by Professor J. B. Cragg, Dr E. B. Worthington, Mr H. C. Gilson and Mr R. Clymo; other points were raised by Dr D. S. Ranwell, Dr J. M. Lambert and Mr Bellamy, who mentioned another example of a roadway acting as a source of calcium.

Completing the afternoon's session, Dr J. Phillipson gave an account of 'The feeding biology of Mitopus morio (Fabricius) (Phalangida, Arachnida)', which he introduced by pointing out that before a reliable picture can be formed of energy transformations within a community, more information must be available on the efficiency with which animals in nature utilize their food materials. The two most often used indices of metabolic activity are the respiratory rate and the 'Konsumquotient'. The former is of great value in studying small organisms whereas the latter has been used for more readily handled species. However, both methods have attendant disadvantages as the experimental animal has to be studied in the laboratory under conditions of temperature and humidity that do not always simulate those of the natural environment. In the present work on M. morio an attempt was made to eliminate these disadvantages and to obtain a measure of the energy transformation brought about by all the developmental stages under natural conditions.

Examination of faecal pellets, laboratory feeding experiments and field observations showed M. morio to be a general predator. Only animals with a thick exoskeleton, much mucus or species much larger than the predator escaped capture.

Knowing the animal's food, laboratory feeding experiments showed that the amount of food assimilated, expressed as a percentage of the weight of food eaten was highest in instar 2 (74 %) and fell to 47 % in the adult. Food consumption under field conditions ranged from 0-46 cal. per day in instar 2 (average live weight 1 mg) to 2-98 cal. per day in adult males (average live weight 26 mg) and 5-74 cal. per day in 6th instar females (average live weight 17 mg). The corresponding average calorific values for food assimilated per day ranged from 034 cal. in instar 2 to 1-39 cal. in adult males and 2-53 cal. in 6th instar females.

The 'Konsumquotient (KQ), expressed as c/3Ig2 where c represents food consump- tion or faeces production and 3,g\ the surface area of the animal, was not approximately constant and therefore not directly proportional to the surface area of M. morio. The 'constant' was affected by the physiological state of the animal and is thus of limited value for the study of metabolic activity.

Answering a variety of questions from Dr S. R. J. Woodell, Dr D. S. Ranwell, Mr E. D. Le Cren, Mr B. Heighton, Dr J. L. Cloudesley-Thompson, Dr J. Morton Boyd, Mr I. J. Linn, Mr J. G. Skellam and Mr G. Williams, Dr Phillipson explained that although the animals may move about in high humidities in the dusk, they are not active hunters; most of their food is taken in the early hours of darkness and capture seems to depend

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British Ecological Society 441 upon physical contact with the prey. During the day shelter is sought under grass, stones, etc.

In the evening an informal dinner in the pleasant atmosphere of the Upper Refectory, University College, was followed by a soiree in the North Cloister, where numerous exhibits were on view. The Botany Department of University College demonstrated some useful ecological apparatus, and Mr R. Clymo showed an apparatus used in water- culture experiments, as well as an exhibit on the problem of the calcicole type of distribu- tion and its investigation. Mr S. B. Chapman contributed illustrations on Coom Rigg Moss, Northumberland, and Mr I. G. Simmons showed a preliminary map of the blanket peat of Dartmoor. The Freshwater Biological Association had on view a sampler for the superficial deposits of the bottoms of lakes and J. H. Belcher demonstrated pigments of lake-bottom sediments. Exhibits of photographs included a selection from Blakeney Point, Norfolk, by R. Brindsen and a selection of aerial photos by Dr J. K. S. St Joseph. Other botanical exhibits were by Mrs J. P. Newbould, on the distribution of Dryopteris borreri Newn. in the British Isles; E. I. Newman on the effects of soil disturbance and soil moisture on Teesdalia nudicaulis; Miss B. C. Barratt on some grassland humus forms, mainly from Malham Tarn, Yorkshire; and D. Munro on trenched plot experi- ments in the New Forest. On the zoological side, Dr D. J. Crisp showed some animals of the east coast of N. America and R. 0. Brinkhurst demonstrated wing polymorphism in the British Gerroidea.

On Saturday morning, 9 January, following the Annual General Meeting (see below), Professor P. W. Richards gave a paper on the 'Peat swamps of Borneo'. In Malaysia extensive peat swamps are found at low altitudes, especially in Borneo, Sumatra and New Guinea. They occur mainly near the coast and always in regions of high rainfall with no well-marked dry season. The peat swamps of north-western Borneo have recently been carefully studied by Mr J. A. R. Anderson of the Sarawak Forestry Department and this paper deals partly with his work and partly with Professor Richards's observations during a visit to Brunei and northern Sarawak in March-April 1959.

The peat swamps have a convex surface and are analogous to the raised bogs of temperate climates. The plant communities form more or less concentric zones and are dominated by trees. In some zones the Dipterocarp Shorea albida is dominant to the exclusion of almost all other tall-growing species. The zonal communities form a series with respect to number of species (which diminishes towards the centre), abundance of Nepenthes and other features.

A boring by Muller and Anderson at Marudi in Sarawak showed that the peat may be as much as 13 m thick and the pollen profile suggests a succession beginning with man- grove and ending with the stunted Combretocarpus-Dactylocladus community ('padang paya'). The radiocarbon dating of peat at 12 m is 4040?70 years.

These peat swamps offer a variety of interesting problems for future investigation. The paper was illustrated by coloured slides and by a collection of aerial and other

photographs kindly lent by Mr J. A. R. Anderson. Following it, questions were asked by Dr A. S. Watt, Dr J. M. Lambert, Dr E. W. Jones, and Dr A. E. Apinis. Professor Richards said that bryophytes do not play an important part in the swamp forests, apart from a number of hepatics on the pneumatophores; otherwise epiphytes are not abundant.

In the second paper, on 'A graphical model representing various mechanisms of population control', Mr G. G. Vickers suggested that a synthesis of all current views concerning the modes of population control depends on clear definition of what are at present somewhat confused concepts. The operation of the population-environment system is still a controversial matter because semantic difficulties obscure the nature of the components and the interactions involved. Synthetic mathematical treatment of the system cannot succeed until the concepts to be manipulated are clearly definable.

Representation of the population-environment system by a physical model may be rewarding, since such a model may be made obedient to many different influences operating simultaneously. Mr Vickers described an earlier attempt to construct a population control model (Proceedings, XV International Congress of Zoology, 1959); this model appears inadequate in that it cannot allow for the fact that mortality is

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442 British Ecological Society imposed simultaneously by many different influences. He outlined a new approach to a model: a population is represented as an elastic body contained within a variable pressure chamber representing ambient physico-chemical conditions. Metabolic process within the population is supported by an energy and a material input, and is subject to a variable load representing diversion of energy from the population. The size of the population will vary according to its metabolic output; this is susceptible of alteration at four control points, namely 1/Energy input, 2/Material input, 3/External pressure, 4/Load imposed.

Energy flux through the population will be adjusted through natality and mortality, and these will be varied by alteration at one or more of the four control points; the controls may be independently operated, interlinked extrinsically, or linked intrinsically through feed-back mechanisms proportionate to the population.

If concepts of population control mechanisms can thus be translated into physical terms, an actual model might be constructed in collaboration with control-system engineers: such a model would enable the possible interactions of the various control mechanisms to be realized. The forms of these interactions could then be compared with field and laboratory studies of actual populations; in this way a closer approach to a truly general theory of population control mechanisms might be made.

The paper was welcomed as a new way of thinking by Mr J. G. Skellam, who, with Professor J. B. Cragg and Mr G. R. Gradwell, selected particular aspects for critical comment.

The final session in the afternoon was opened by Dr G. M. Dunnet, speaking on 'A study of a population of rat-kangaroos (Setonix brachyurus) using the recapture technique'. This paper was an outline of a study of the quokka (S. brachyurus) in its semi-natural habitat on Rottnest Island, off Freemantle, Western Australia. The quokka is a small wallaby, comparable in size with the brown hare, and is herbivorous and mainly nocturnal. During the study over 3000 were caught and tagged, and over 5000 captures were recorded. The animals occur all over the island, and on the eastern end, during the hot dry summer months of December-March they congregate at night on a limited number of fresh or brackish water seepages, to drink. Movement of tagged animals in relation to the seepage was described and it was concluded that several remarkably discrete sub-populations of quokkas exist in different areas of the island, those on the western areas not coming to the drinking places at all.

Young quokka remain in the pouch for about 5 months and by measuring them at each capture, growth-rates and birth-dates were calculated. The season of birth extends from late January to early November, but most young are born in February, March and April. Growth and size of different age-groups was described.

The main object was to estimate population size and death-rate using the recapture technique and after several trapping procedures had been tried, the most attractive seemed to be the use of a long net at the drinking places throughout the summer. A sampling programme involving netting at 2-hourly intervals from 9.00 p.m.- 2.00 a.m. on three consecutive nights, once in each monthly period, gave usually between 100 and 200 captures per month. The nature of the sample was considered in detail and thought to be consistent with random sampling in regard to drinking behaviour throughout the night and constancy of place and time of drinking, but young animals in general tended to be caught more readily than old ones and in the estimation these had to be con- sidered as two separate populations. It was also considered that the problem of trap addiction and probably trap-shyness had been eliminated, at least to some extent, in the inter-period analyses.

Despite these apparently favourable circumstances, and with the order of 45-60% of the population marked in each of 3 years, only very approximate estimates were obtained. Not only were these estimates imprecise but their relation to the population may be questioned. Thus, samples from populations of which some individuals are marked can tell us much more about the biology of a species than sampling without marking, but the use of the recapture technique for the estimation of population para- meters must always be investigated with special care.

The merits of the recapture technique were discussed by Mr E. D. Le Cren, Dr R. 0.

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British Ecological Society 443 Brinkhurst, Professor 0. W. Richards, Mr J. G. Skellam, Dr D. H. Chitty, and Mr H. N. Southern.

The final two papers were both concerned with the ecology of the South Atlantic islands (the Tristan da Cunha-Gough Island group). Mr N. M. Wace spoke on 'Some aspects of plant ecology and phytogeography in the South Atlantic islands'. The Tristan da Cunha-Gough Island archipelago in the South Atlantic is a remote group of oceanic islands, probably formed very recently, and having a warm temperate hyper-oceanic climate. On Gough Island, five vegetational formations can be recognized.

Maritime Tussock Grassland on the sea cliffs and in penguin rookeries, formed by Poa flabellata, closely resembling some tussock communities in the New Zealand shelf and southern Indian Ocean islands, and with some similarities to grass steppe. On all the islands in which it occurs this formation is very vulnerable to the effects of grazing animals.

Fern Bussh which is dominated by Phylica arborea, forming dense thickets amongst the small tree-fern Blechnum palmiforme, and Histiopteris incisa. Mosaic formation by the different components of this community is dependent upon autogenic cyclical processes involving the rapid build-up and slipping away of peat accumulating on the steep slopes. The formation is structurally related to widespread tropical mountain vegetation types ('mist forest', 'microphyll mossy thicket', 'heath forest', 'elfin woodland'), and is unlike the southern continental Nothofagus forests.

Oceanic Heath, forming blanket peat above the Fern Bush and Tussock Grassland communities, dominated by Empetrum rubrum, grasses and sedges, with patches of Sphagnum and other bryophytes. This community resembles structurally the Magellanic moorland of western Chile, and the wet moorland vegetation of western Europe.

Feldmark in the most exposed areas above 750 m, with isolated tufts of Agrostis media, mats of Empetrum and Rhacomitrium, and hummocks of close-growing bryophytes. This community on Gough Island lacks the cushion-forming flowering plants of higher southern latitudes (Azorella, Colobanthus).

Bogs of deep (to 4X5 m) Sphagnum and Cyperaceae peat, formed in the mountain valleys, resembling structurally the dissected montane valley bogs of north-west Europe. Shallower and less dissected peat deposits formed by Bryales and Hepaticeae cover some of the mountain plateaux. Bogs dominated by cushion-forming flowering plants (Donatia, Astelia, etc.) as found in New Zealand and South America do not occur in the Gough-Tristan group.

Some of the ecological effects of their insularity and oceanic climate include:

(i) The high proportion of pteridophytes to flowering plants (27/32 species on Gough, cf. 34/about 325 native on Rhum), correlated with the great importance of ferns in the vegetation.

(ii) The extreme species-poverty (0 5 native flowering plants per square km on Gough, cf. 3 0 native fl. plants/sq. km on Rhum) and lack of annuals, together with the lack of species adapted to withstand the conditions created by man (grazing, clearance, fire, etc.), leading to vegetational imbalance and vulnerability to changed conditions or competition from new arrivals.

Owing to these peculiarities, the island formations are not strictly comparable to continental climax formations because the species present on the islands are selected primarily for their capacity to achieve long-distance dispersal. Structural rather than floristic or phytosociological criteria must be used in comparing their vegetation with that of other areas.

Comments on the effects of grazing on the Tussock Grassland were made by Professor J. B. Cragg, Dr E. J. Godley and Dr G. M. Dunnet.

Dr M. W. Holdgate, in the last paper, considered some 'Aspects of animal ecology in the South Atlantic islands'.

The Tristan da Cunha-Gough Island group has an impoverished and disharmonic terrestrial fauna. One hundred and thirty-two species have been recorded and of these forty-five are probably alien: about 65 % of the native species are believed endemic. The fauna shows strong South American relationships and is thought to have invaded

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444 British Ecological Society the islands comparatively recently largely by airborne immigration in the prevailing westerly winds.

A study of selected habitats emphasizes the poverty of the fauna. On Gough Island only eight species have been recorded in fresh water, and two of these are known else- where only from marine habitats. Three of the remaining six are carnivorous, and a Dytiscid beetle (Lancetes varius F. dacunhae Brinck) ranges most widely of all. Various features suggest a low level of interspecific competition and probable underexploitation of the habitat. These features are also apparent in terrestrial situations. Many of the common plants are attacked only by one or two phytophagous species: for example one Lathridiid beetle (Coninomus sp.) is alone abundant on the fern Histiopteris incisa, a Delphacid (Delphacodes atlanticus China) and a weevil, Tristanodes sp., are associated with Sciryus spp. and two or three aphids with Apium australe. Some niches seem to be unfilled, there being for example no specialized wood-boring insect larvae which attack the dominant tree Phylica arborea. Yet despite this poverty of species and aspect of underexploitation, the numbers of individual animals appear high, and in terms of the production of animal matter the islands may not differ significantly from continental areas.

Detailed quantitative studies are urgently needed in undisturbed oceanic islands of this kind, and the small number of interacting species may permit the assessment of the role of each one in the ecosystem.

Time was unfortunately not available for discussion of this paper. The meeting's thanks were expressed to Professor D. Lewis for the hospitality of his

Department, and to Dr and Mrs P. J. Newbould and their helpers for making the local arrangements.

THE ANNUAL GENERAL MEETING

The 41st Annual General Meeting began at 10 a.m. on Saturday, 9 January 1960. The following are the (unconfirmed) minutes of this meeting.

MINUTES OF 41ST ANNUAL GENERAL MEETING

The President, Professor N. A. Burges, took the chair in the Lecture Theatre of the Department of Botany, University College, London, at 10 a.m. on 9 January 1960.

(1) The minutes of the 40th Annual General Meeting, having appeared in J. Ecol., 47, 3, and being due to appear in J. Anim. Ecol., 28, 2, were taken as read, and approved.

(2) The following report of the Hon. Secretaries had been duplicated and circulated to members attending the meeting:

Report of the Honorary Secretaries for 1959 Meetings

During 1959 effect was given to the recommendations of the Programme Planning Committee constituted the previous year. Besides the Winter Meeting in Oxford devoted to a variety of ecological subjects, and the Summer Field Meeting in Galway, two specialized meetings were held in the spring-one on Freshwater Ecology at Reading and the other an intensive, four-day symposium on the Biology of Weeds at Oxford. In terms of attendance the response to these arrangements has been most encouraging: all were well attended, the numbers exceeding 100 at Oxford (January), 40 in Galway, 70 at Reading and 160 at Oxford (April).

The 40th Annual General Meeting of the Society was held during the Winter Meeting in the Department of Zoology and Comparative Anatomy, University of Oxford. The President, Professor N. A. Burges, took the chair at 10 a.m. on 3 January 1959. An account of the proceedings has appeared in J. Ecol., 47, 3, and will appear in J. Anim. Ecol., 28, 2.

Papers were read on Friday afternoon, 2 January, as follows: Miss K. Paviour-Smith- 'The insect inhabitants of the birch-bracket fungus'; Professor W. T. Williams-

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